Decomposition of Cellulose to Produce 5-Hydroxymethyl-Furaldehyde in Subcritical Water

Trans. Tianjin Univ. 2008, 14:198- -201DOI 10. 1007/s12209-008-0036-4@ Tianin University and SpringerVerlag 2008Decomposition of Cellulose to Produce 5-Hydroxymethyl-Furaldehyde in Subcritical WaterLU Huisheng(吕惠生), LI Xiangke(李向科), ZHANG Minhua(张敏华)(Key Laboratory for Green Synthesis and Conversion of Ministry of Education of China;R&D Center tor Petrochemical Technology, Tianjin Universily, Tianjin 300072, China)Abstract: A method for decomposition of cellulose to produce 5-hydroxymethyl- furaldehyde (5-HMF) in subcritical water- carbon dioxide binary system was proposed. A series of experiments wereperformed in a batch reaction vessel. Main products of the decomposition of cellulose are 5~HMF ,furfural, levulinic acid and 1, 2, 4-benzenetriol.The optimum condition for the preparation of 5-HMFwas found as 523.15 K, 5.0% carbon dioxide mole fraction, and 30 min reaction time. The addi-tion of carbon dioxide to water conduced to the decomposition of cellulose to 5-HMF. As can beseen from the distribution of the prod-ucts, the decomposition mechanism of cellulose is similar tothe hydrothermal reaction of D-glucose and D-fructose.Keywords: cllulose; 5-hydroxymethyl-furaldehyde; water-carbon dioxide binary system; subcritical waterCellulose is the most abundant biomass resource, duced to the decomposition of cllulose. Moreover, aferwhich can be used to produce energy and various chemi- the reactin, carbon dioxide can be easily separated fromcal intermediates and materials. Cellulose is a kind of the system. This is a green process.renewable resource, and this is important to solve thecurrent energy problem from the lack of fossil fuels. Cel-1 Experimentallulose is a β-(1, 4)-linked homopolymer of many anhy-1.1 Chemicalsdroglucose residues and can be easily hydrolyzed by add-ing acid catalysts and enzymes to cellooligosaccharidesMicrocrystalline cellulose (> 97%), CO2 (99.9%),and glucose. In recent years, some studies on the non- acetonitrile (analytic purity), S-HMF (>98%), D-glucosecatalyzed hydrolysis of biomass in subcritical and super-(analytic purity), D-fructose (analytic purity).critical water with the absence of any catalyst have been1.2 Apparatus and procedureperformedl- 9. Their goal products mainly focus on theThe decomposition experiments of cellulose werecellooligosaccharides or glucose for the fermentationcarried out in a batch reaction vessel (PARR Instrumentalcohols. And it is exigent for the experimental equip-Co, USA, PARR-4575A) with volume of 500 mL. Thement to perform the experiment at the crtical point of maximum temperature the vessel can endure is 500 C,water at high temperature and pressure6. However,and the maximum pressure is 34.5 MPa. The processmany other chemicals can be formed in the reactionflow diagram of experiments is shown in Fig.1. The ex-process in subcritical water or high-temperature water/.perimental procedure is as follows: first, 2.025 g cellu-In this paper, H2O-CO2 binary system was selectedlose and 150 g distiled water were put into the reactionas the reaction medium, and S-hydroxymethyI- vessel which had been purged with CO2 gas for threefuraldehyde (5-HMF) was found to be an interestingtimes; then, a certain amount of CO2 was added into theproduct in the decomposition of cellulose under the ex-vessel, which was measured exactly by a mass flowmeter;pcrimental conditions. In the binary system, carbon di- after that, the vessel was heated by an etrical heatingoxide was added to the water and reacted with water,jacket, during which, the temperature was monitoredforming carbonic acid, so the concentration of hydrogenand controlled by a temperature controller (PARR In-ion in the solution was higher than that in pure water, strun中国煤化工and the pressure wasand the acidity of the system was enhanced, which con- moni:YHC N M H GDuring the reactionAccepted date: 2008-01-03.LU Huisheng, born in 1963, male, associate Prof.Correspondence to ZHANG Minhua, E-mail: mhzhang@tju.edu.cn.LO Huisheng et al: Decomposition of Cllulose to Produce S-Hyroxymetry-Furaldehyde in Subritial Waterprocess, samples could be taken out from a sample pipe 2 Results and discussionat different intervals.2.1 Products distributionVent16C 2 VentIn this process, the hydrothermal decomposition ofcellulose was affected by the temperature, the reaction的time and the mole fraction of CO2 in H2O-CO2 binarysystem, so the influence of these conditions on the yieldof 5-HMF was studied.The experiments on cellulose decomposition were| |co，carried out at 230 C, 250 C and 270 C. The mole frac-tion of CO2, xco, at different temperatures varied frompump:;6-Cylinder bomb; 7- Stirrer, 8-Safty rupture dise; 9-Gas re-0.0% to 7.5%. Typical product distribution is shown inpump; 6-lease valve; l0-Liquid sampling pipe/gas inlet pipe; 11- Presure gaugc;Fig. 2, and the main products are 5-HMF, furfural, levu-12- Temperature controller; 14- Sampler.linic acid, and 1, 2, 4-benzentriol.Fig1 Scheme for decomposition of cllulose3.0x10F5-HMF 523.15 K,7.5% CO,30 min.3 Analysis2.5x 10'-The aqueous product solution collected was qualita-2.0x 10tively analyzed by the GC-MS system (Agilent 6890-5973)昌1.sx10'-with the column HP-5ms (0.25 mmx 30 m). The sample1.0x 10'Furfural1.2,4-benzenetriolinjection volume was 1.0 μL. The thickness of liquidLevulinic acid Imembrane was 0.25 μm. The temperature of the vapor-0.0245678910145Tine/minizer was 473.15 K. The temperature of the column wasTime/minfirst controlled at 353.15 K for 2 min, then increased toFig.2 GC chromatogram for decomposition products453.15 K at the speed of 10 K/min, and sustained for 2distribution of cellulosemin. He was used as carrier gas, and the flow rate was2.2 Factors affecting the reaction1.5 mL/min. The scanning scope was 10- 500 amu.2.2.1 Reaction timeThe content of 5-HMF, which was a main productThe experimental results are shown in Fig. 3. Therein the aqueous solution, was quantified by the HPLCis an optimum reaction time at each temperature andsystem (Agilent-110) with a Zorbox C18 column and aCO2 mole fraction, when the mass yield of 5-HMF has a .UV detector. The operating temperature of the columnmaximum value. 5-HMF is not very steady in high tem-was maintained at 303.15 K The mobile phase was theperature water, and can be transformed into other sub-solution of water and acetonitrile (the volumetric ratio ofstances. During the initial stage of the reaction, there iswater to acetonitrile ws 90 : 10) with a volumetric flowmore cellulose than 5-HMF in the system, and the con-rate of 1.0 mL/min. The sample injection volume wasversion of cellulose to 5-HMF is the main reaction, so1.0山. The detection wavelength was 280 nm.the mass yield of 5-HMF increases gradually. But afterThe mass yield of 5-HMF, YsHMP> was calculated bythe optimum reaction time, cellulose is ltle, and thethe equation:further conversion of 5-HMF becomes the main reaction,Y.MF=.10.0xu nv x100%0so the mass yield of 5-HMF decreases gradually.2.025x0.97where 150.0 stands for the weight of decomposition solu-2.2.2 TemperatureThe effect of temperature on the maximum masstion in gram, because water is excessive enough andyield of 5-HMF is shown in Fig. 4. Between 503.15 Kthere is certain mass loss during sampling process, thand 543.15 K, the yield has a maximtm value at 523.15mass of water is substituted for the mass of decomposi-K atcn be concluded thattion solution, 2.025 is the weight of microcrystalline cel-the f中国煤化工_3ger than its conver-lulose, and 0.97 is its purity; W.HMF is the mass fractionsionTYHCN M H Gr that its formationof 5-HMF in decomposition solution.rate is smaller than its conversion rate. The decomposi-一199-Transactions of Tianjin University Vol.14 No.320082. 5%co,is 523.15 K, and at this temperature the maximum masst中7.5%CO,5.0% Co;yield can be up to 16.19% when the reaction time is 30min and the CO2 mole fraction is 5.0%.2.2.3 CO2 mole fractionThe effect of CO2 mole fraction on the maximummass yield of 5-HMF at different temperatures is shown20406080100120140in Fig. 5. The yield of 5-HMF in H20-CO2 binary systemReaction time t/minis obviously higher than that in the system without CO2(a) T=503.15 KIt can be explained that the acidity of the system is en-8-5,.0% Co,hanced because of the introduction of CO2 The reac-16-tions in H20-CO2 binary system are as follows:12个CO2(g) = CO2(aq)(1)g1CO2(aq)+ H20= H,CO3(2)H2CO, = HCO~;+H+(3)HCO;=CO}-+H+(4)40506070H20 =0H+H+(5)20一503.15K(b) T=523.15 K523.15K+543.15K8t●0.0%CO,5147.5% CO2121co, molo ftocom‘810203040S060Fig.5 Effect of CO2 mole fraction on the maximum massyield of 5-HMF at different temperatures(C) T=S43.15KFig.3 Effect of reaction time on mass yield of 5-HMFCO2 reacts with H2O to form HCO3, So the concen-at dfferent temperatures and CO2 mole fractionstration of the hydrogen ion in the system increases, dueto the ionization of H2CO3, These reactions exist under18t0.0% cO,- 2.5% CO,subcritical H20-CO2 conditions(8- -10. The enhancement- 7.5% Co,of the acidity can promote the dehydration of the sac-chrides, so it is helpful to produce 5-HMF.However, when the CO2 mole fraction exceeds 5.0%,the yield of 5-HMF no longer increases obviously; oreven begins to decrease at 543.15 K. Because carbonic30051052053054550acid is a kind of weak acid, its ionization ability is lim-Tempcrature TIKited. With more and more CO2 introduced into the sys-Fig.4 Effeet of temperature on the maximum mass yieldtem, the concentration of hydrogen ion increases slowlyof 5-HMF at diferent CO2 mole fractionsdespite the growing amount of CO2 in aqueous solution.tion of the cellulose is a complicated system, and the In this way, the yield of 5-HMF can hardly increase.products distribution is more comprehensive when the 2.2.4 Optimum condition for the preparation of 5-temperature is higher. The existence of side reactionHMFaffects the yield of the target product. Although the high中国煤化工an be concluded thattemperature contributes to the further conversion of 5- the opCaration of 5-HMF isHMF, when it exceeds a certain limit, it is disadvanta- as foll:YH. CN MHCGconoleraetion 08geous to 5-HMF. So the optimum reaction temperature5.0%, and reaction time of 30 min.一200-L0 Huisheng et al: Decomposition of Cllulose 10 Produce S-Hyroxymethy-Furaldehyde in Subcritical Water2.3 Formation mechanism of 5-HMFHMF,Under the optimum condition for the preparation(2) Optimum condition for the preparation of 5-of S-HMF, D-glucose and D fructose were hydrother- HMF is as fllows: temperature of 523.15 K, CO2 molemally treated. And the results of GC-MS are shown in fraction of 5.0% and reaction time of 30 min.Fig.6. The decomposition product distribution of D-(3) The formation mechanism of 5-HMF from cellu-glucose and D-fructose is completely the same with that lose is similar to that of D-glucose and D-fructose.of the cellulose. Main products are still 5-HMF, furfural,Referenceslevulinic acid, and 1, 2, 4-benzenetriol.[1] Sasaki M, Kabyemela B, Malaluan R. Cellulose by-[ 523.15 K.5.0% CO,drolysis in subcritical and supercritical water [J] .30 min5-HMFJournal of Superical Fluids, 1998, 13(1/2/3):261-268.Furfural1,2,4-benzenetriol[2] Sasaki M, Fang Z, Fukushima Y et al. Dissolution andLevuliaic acidhydrolysis of cellulose in subcritical and supercriticalCellulosewater [J]. Ind Eng Chem Res, 2000, 39 (8): 2883-2890.Glucose[3] Kruse A, Gawlik A. Biomass conversion in water at330- -410 。C and 30- -50 Mpa: Identification of keyFructosecompounds for indicating different chemical reactionTime/minpathways [J] . Ind Eng Chem Res, 2003, 42 (2): 267-279.Fig.6 Identified compounds chromatogram of[4] Sasaki M, Adschiri T, Arai K. Kinetics of cellulosedecomposition materials of cellulose, glucoseconversion at 25 MPa in sub- and supercritical waterand fructose in H2O-CO2 binary system[J]. AIChE Journal, 2004, 50 (): 192-202.It can be seen that there are similar products from[5] Sakaki T, Shibata M, Hirosue H . Decomposition ofcellulose in near critical water and fermentability ofthe three materials. During the decomposition process ofthe products [J]，Energy and Fruels, 1996,10 (3): 684-the cellulose, D-glucose and D-fructose were not found688.in the decomposition product distribution. One possible[6] Li x Y, Sakoda A, Suzuki M . Kinetics and productreason is that they are unstable intermediates, the otherdistributions of cellulose decomposition in near criticalreason is that their dehydrates were directly produced towater J] . Journal of Chemical Industry and Engineering5-HMF under hydrothermal conditions. This problem(China), 2001, 52 (6): 556-559(in Chinese).[7] Akiya N, Savage, P E. Roles of water for chemical reac-needs further study.tions in high-temperature water J]。Chem Rev, 2002,So the formation of 5-HMF can be described as102 (8);: 2725-2750.C.H2O。- "”HO-CHO+3H2O[8] Takenouchi s, Kennedy G C . The binary system H2O-CO2 at high temperatures and pressures J] . AmericanJourmnal of Science, 1964, 262 (11): 1055-1074.[9] Todheide K, Franck E U. The two-phase region and3 Conclusionsthe critical curve in the system carbon dioxide-water atpressure up to 3 500 bar U]. Z Phrys Chem (Munich),(1) H20-CO2 binary system is a kind of green reac-1963, 37: 387-401.tion medium to treat some biomass resources. The addi-[ 10] Bignold G J, Brewer A D, Hearn B . Specific conductiv-tion of CO2 to water improves the acidity of the system.ity and ionic product of water between 50 and 271 CThis contributes to the decomposition of cellulose to 5-[J] . Trans Faraday So, 1971, 67 2419-2430.中国煤化工MYHCNMHG一201一